Rough Idle - Chevy 350 TBI

[DerekTheGreat]

Not using oil is a plus. With our K1500 I just buy two 5qt jugs at each oil change, one for the change and then one for in between.. For the truck I'm going to keep doing the Seafoam thing just 300 miles before an oil change for a while. Lincoln is getting Seafoam in it's crankcase this afternoon.

Should be good for the car. When I'm on the freeway it amazes me how many new/late model cars throw black smoke out of their tailpipes when they let loose..

Not having a big fleet or a lot of overhead helps to keep prices competitive I think too. I won't try to dig too deep into the economics of that type of stuff as my opinions could probably write a novel and then I'd have arthritis in my hands...

That's how I'd do it. Nothing like getting into a car only to question if it will actually make the trip due to lack of maintenance..

Being a jack of all trades also helps in keeping expenses down and more money in your pocket too. I prefer low stress.

Was also thinking the problem to my truck could be a burnt up valve but without doing a compression check I'll never know. Guess I should just buy a tester or drive the thing as is.

 

[MouthForWar]

I need to do a compression check on the truck at some point as well. Will be on the top of the to-do list once she's put back together. Might help me zero in on my low oil pressure.

I'm hoping that doing the intake mani at least cured my stumble though, that way I can hone in on the low oil pressure issue and also start rebuilding the steering/suspension. Looks like the PO hasn't done the ball joints/TREs/control arm bushings in....ever. Lol. Plus I'd like to throw some shocks on there.

This truck is quickly turning into a massive project. I haven't even gotten to interior/exterior **** that needs replaced. Tailgate, grill, door panels, headlight/taillight assemblies, wheels....ugh. Lol.

Fusion continues to run absolutely outstanding after the crankcase treatment, btw. Will probably do another round at the end of the next OC cycle just to make sure I cleared out the last of the gunk.

 

[DerekTheGreat]

Hmm. I'm no expert but suspect that if it snapped a rod you'd hear that clanging away or if it snapped it right at the rod cap & magically left the piston and it's remains at TDC you'd have next to no oil pressure due to all of it squirting out the wide open gallery where the connecting rod & cap used to be. These things seem to **** the sending unit after awhile. Our C3500 did that and so I had it towed to the shop, ignoring the fact that I didn't hear valvetrain noise. Gage said 0 or just above it so I got worried. Was just the sending unit. I think on tree-fiddy's & tree-oh-fives the sending unit is just behind the distributor off to the driver's side.

Since you said those gaskets were wasted it most likely did something for the truck. I put an idler arm & pitman arm on our K1500 when we first got it as all that was loose. Took it for an alignment and figured the ball joints and such had to have been done sometime in the past due to all the miles but the dude at the tire shop said they were most likely original. Said they weren't sloppy so I've just been greasing them. Just put shocks on ours, redid the brakes at all four corners and other ****, stupid electrical stuff for the HVAC, fixed inop taillights, blah blah.

Every GM truck we've bought has been a project, they've always needed more than our Fords. Hoping now that despite it's crappy idle, the k1500 will do what most people say they do, "It might run like **** but it'll run like that longer than most cars run at all."

Sweet. It's certainly something I'm a believer in. Of course, you could make the **** yourself with some IPA and mineral spirits. It may also have a hint of Acetone in it too. I'm lazy and prefer to just buy it ready to go.

 

[MouthForWar]

Yea, the sending unit was the first thing I replaced after lurking around here for a while and seeing it as a common issue. Wasn't the issue, but oh well. Also had to do the infamous o-ring & gasket on the oil filter elbow; it was leaking pretty good.

I'm a little concerned my cam bearings might just be worn down too much, which is another big cause of low oil pressure in these things. That's a much bigger project than I'm willing to put the time and effort into right now though. Haha. We'll see what the SeaFoam treatment does in the truck and go from there.

 

[DerekTheGreat]

My o-ring & gasket for the elbow were also trashed, bad bad oil leak. Guy we bought it from was just driving around like that, must've been 80miles or less to a quart of oil.

Hmm, well hopefully the seafoam does something for your truck. You could also put that Restore stuff in, that helps a bit. Certainly helps compression.

 

[DerekTheGreat]

After "leveling up" my engine diagnosis skills by scouring YouTube I have deduced our truck's problem is a burnt valve... I held a piece of paper near the exhaust and at times the paper gets sucked onto the tip. Yay. Anyone ever drive something like this for a long time? What should I expect over the long haul or should I just throw some good Vortec heads on it? I have the old heads that came off my 305TBI Fireturd...

 

[GMCTRUCKS]

I changed out my spark plugs in my 1993 GMC after well over 120K miles last week I did change out the wires twice in those miles I use MSD 8.5 wires and NGK plugs and box and the only time I had a miss was when my dizzy was cracked and how I found it I covered the dizzy with a plastic bag and in the morning I took it off and no engine miss so I changed it out oh currently I have 201K miles.

 

[DerekTheGreat]

You not have burnt up valve, head gasket or intake manifold woes then. This truck has a new distributor, A/C Delco plugs, wires cap and rotor. Somebody fed this thing a hot supper. I was initially impressed by how nice the coolant looked and there was no rusty schmoo in the reservoir or radiator but I'm guessing that's because the ******* had already done ran hot multiple times before the PO's got around to fixing all of that.

 

[MouthForWar]

Hey, so...reporting back. Got everything put back together and a few issues sorted out. Truck runs freaking strong. Only have a couple hours of runtime on it, but it hasn't stumbled on me yet...even when really hot. So that's good.

I do have a slight amount of moisture just on the front side of my intake mani though, along that valley wall; apparently I didn't get crazy enough with the RTV along that wall. Frustrating, but I am so not about to pull it all apart and do it all again right now though; it's a very minute amount, not anywhere close to a steady leak, and the truck runs strong. So meh.

Still have low oil pressure at hot idle when in gear, but I haven't SeaFoamed the crankcase or anything yet. That's next on the problem list to zero in on. Just wanted to say that doing the previously grenaded intake mani gasket seemed to help the stumble a bit, along with advancing the timing just a hair. (We got the initial timing 3 degrees advanced when putting it all together; decided to just leave it there due to our altitude [7200 Ft.] and the fact that it runs so good...figured might as well leave well enough alone). So yea, for what all that is worth.

Obviously an intake mani gasket and advancing your timing isn't going to do **** for you if you have a burnt valve though, lol.

 

[DerekTheGreat]

Glad to hear the new intake gaskets cleared things up on your end. Our truck does not like timing advance at all. Weird acceleration when at part throttle, it kind of stammers. Full throttle and cruise is fine though. No codes any more but was giving me code 42 or 43 when the dizzy was first swapped. Just going to run it until it explodes or we sell it. Looking for an engine but the search isn't going so well.